1. Field of the Invention
This invention concerns the elimination of voltages not in the Bandpass of the filter, A.C. or D.C. voltages.
The proliferation in the use of integrated circuits in home controls and electronics, telecommunications, commercial and industrial controls, and the computer field has resulted in the desirability of a circuit that will eliminate transient spikes and suppress over-voltages that destroy IC's. This invention provides such a circuit. It also has the capability of passing audio, Tip and ring voltages, data transmission and touch tone frequencies for both the input phone lines and the output phone lines and remotes of a PBX and other systems. The circuit removes over-voltages caused by lightning strike and man-made equipment.
2. Background Art
Crosby et. al. utilizes a series tuned circuit comprised of 2 capacitors 5 & 6 and 2 inductors L7 & L8. A series tuned circuit has a lower Q of resonance and a wider Bandpass than the Pi Network used in our circuit, which demonstrates a high Q and sharp slopes to cutoff of Bandpass voltages. To bleed-off the over-voltage we use a minimum of 4 caps and 2 inductors, MOV's and gas charge tubes as voltage reducers. There is no need for current limiting as the load will only pull the current consumed normally. SUMMARY
My high Q, narrow Bandpass filter acts as a spike eliminator of lightning strike spikes which have higher frequency components. The gas discharge tube voltage limiters and MOV's reduce the voltage level required to protect our bypass capacitors from over-voltage. As a practical matter, a Micro-Second (10-6) is about the best response time achievable with known transient surge suppression devices which includes gas discharge tube, MOV's, Zener diodes and other solid state devices. The Bandpass Filter stops voltages out of Passboard frequencies. This prevents spikes from reaching the load. The Bandpass Filter's high impedence stops the transient spike to allow the voltage rise and removal of the over-voltage by the MOV. The MOV operates at 121% above normal line voltage. My capacitors are set up for voltage rise to the MOV activation plus a safety margin. This insures repeat performance and longer circuit life.